1. Field of the Invention
This invention relates to a process for manufacturing a highly efficient antislipping agent composed of acrylic copolymers based on small amounts of solid content; wherein two kinds of acrylic latexes composed of small amounts of solid content are prepared by using pertinent acrylic monomers in low or high glass transition point side, being well blended and homogenized by neutralizing with ammonia water.
2. Description of the Related Art
According to the composition of antislipping agents in the first stage, some hot-melt adhesives were coated along several lines on the surfaces of packaging boxes made of craft paper, the adhesives proved to have antislippling effects owing to its initial strong adhesive strength when stacking packaging boxes and some disadvantages were recognized in that a) separation between packaging boxes were difficult, and b) after separation, the packaging surfaces are torn or stained, thus inflicting some damages to the surfaces due to extremely strong adhesive strength [Japanese Patent Unexamined Publication No. 1-183596(1989)].
To be free from weak points, some antislipping agents as a hyblid of inorganic and organic substances were developed:
a) Inorganic substance included silicahydrosol containing 20 to 30 wt % of colloidal silica whose particle size was in the range of 10 to 20 .mu.m. Silicahydrosol in liquid phase was useful not to be whitened in handling when coated or dried. Now that said the size was too small, however, its homogeneous dispersion was so difficult that desirable antislipping effects could not be gained [Canadian Patent No. 1,156,803(1980), Japanese Patent Unexamined Publication Nos. 2-245086 (1990) and 4-303653 (1992)]. PA1 b) Organic substance composed of stylene and acrylic acid as well as some composition with reactive groups proved to have less antislipping effects [Japanese Patent Unexamined Publication No. 57-565989 (1982)]. PA1 1) through the emulsion polymerization between acrylic monomers of 20 to 80 wt % with glass transition point(Tg) in the range of -85 to -5.degree. C. and acrylic monomers of 20 to 80 wt % with Tg in the range of 8 to 153.degree. C., an acrylic latex with relatively low scope of Tg is prepared; PA1 2) through another emulsion polymerization in another container between acrylic monomers of 10 to 60 wt % with Tg in the range of 8 to 153.degree. C. and acrylic monomers of 40 to 90 wt % with Tg in the range of -85 to -5.degree. C. an acrylic latex with relatively high scope of Tg is prepared; and PA1 3) the acrylic latex mentioned in the step 2) of 5 to 60 wt parts is chemically blended with that in the step 1) of 100 wt parts, and the blending is completed by neutralizing with ammonia water.
Further, some antislipping agents containing inorganic and organic substances concurrently included a composition in which synthetic resin binder, using silica powder and poly(acrylamide) treated with nonionic cellulose derivatives as a protective colloid, was dispersed in water. After the agents were coated or dried, they showed good antislipping effects but when used repeatedly, its antislipping effects become deteriorated and in particular, a poor dispersion of antislipping agent itself affected its storage stability badly [Japanese Patent Unexamined Publication No. 59-4460 (1984)].
In view of facts above-mentioned, there were some methods in which a part of resin with adhesive strength was blended to ethylene-vinyl acetate copolymer emulsion, followed by additional blending of silica, fillers and releasing agents. However, the methods proved to have insufficient antislipping effects and when packaging boxes were separated, their surfaces were torn off or contaminated owing to its extremely strong adhesive strength or the lack of reutilization [Japanese Patent Unexamined Publication No. 54-65385(1988), 62-70461(1987), 62-110997(1987) and 4-198373(1992)].
Recently, some latex-typed antislipping agents using nonionic surfactants as a emulsifier were developed. Each particle in the latex consists of both a core as a hard segment and a shell as a soft segment and when drying, it showed good antislipping properties. But since there was no distinction between hard and soft segments with increasing of solid content in the latex, it was still difficult to prepare a latex with storage stability [Japanese Patent Unexamined Publication No. 4-306273(1992)].